Flipped Lesson: Projectile Motion

Overview

Students learn the content at home from the Projectile Motion video, then spend the full lesson solving problems, testing predictions and collecting data. The teacher's job in class shifts from explaining to diagnosing and coaching.

By the end, students can:

1. Explain why horizontal and vertical motion are independent, and why horizontal velocity stays constant.

2. Resolve a launch velocity into horizontal and vertical components.

3. Calculate time of flight, maximum height and range for a projectile launched horizontally or at an angle.

4. Predict where a projectile will land and test the prediction experimentally.

Why flip this topic: the equations are quick to explain on video, but students struggle when applying them. Moving the explanation out of class frees up 40+ minutes for the part that actually needs a teacher: working through problems and fixing misconceptions in real time.

Before class (homework, about 20 minutes)

Students watch the video, fill in a short guided-notes sheet, and submit a 5-question check the night before. Set the deadline early enough that you can glance at the results before the lesson.

Step 1: Watch the video

Watch the Projectile Motion video on physicshigh.com/projectile. Pause and rewind as often as you need; that's the advantage of learning from a video.

Step 2: Guided notes

Answer these while you watch:

1. Sketch the path of a projectile. Draw the horizontal and vertical velocity vectors at the start, the top and just before landing.

2. What is the acceleration in the horizontal direction? In the vertical direction?

3. Write the equations for the horizontal and vertical components of a launch velocity u at angle θ.

4. Which quantity is the same for both the horizontal and the vertical motion?

5. Write down one thing from the video you're unsure about or want to ask in class.

Step 3: Check-for-viewing quiz

Set these up in a Google Form, Microsoft Form or your LMS so you get the results as a spreadsheet. Use g = 9.8 m/s².

1. A ball is thrown horizontally off a cliff. Ignoring air resistance, its horizontal velocity: (a) increases (b) decreases (c) stays constant (d) becomes zero at the top

2. At the highest point of a projectile launched at 30°, its acceleration is: (a) zero (b) 9.8 m/s² down (c) 9.8 m/s² up (d) horizontal

3. One ball is dropped and an identical ball is fired horizontally from the same height at the same moment. Which lands first? (a) the dropped ball (b) the fired ball (c) they land together (d) it depends on the speed

4. A ball is launched at 20 m/s at 30° above the horizontal. Its horizontal velocity component is: (a) 10 m/s (b) 17.3 m/s (c) 20 m/s (d) 11.5 m/s

5. Confidence check: How confident are you that you could solve a projectile problem on your own? (1 to 5)

Question 5 isn't marked. It tells you who knows they're stuck, and who's confident but wrong, which is the more important group to find.

In class (60 minutes)

The lesson opens with the quiz results, not a recap of the video. Students then move from a demo, to whiteboard problems, to a prediction they test with real data.

Opening: use the quiz, don't re-teach the video

If most students got a question right, skip it. If question 1 or 3 was missed by a lot of students, that's the misconception to target in the demo. If students who rated themselves 4 or 5 got questions wrong, pair them with someone who got them right.

Predict–Observe–Explain: the coin drop

Place one coin on the edge of a desk and another on the end of a ruler. Flick the ruler so one coin flies off horizontally while the other drops straight down.

1. Predict: Students write down which coin lands first, and why, before you do anything.

2. Observe: Run it a few times. Students listen for one "click" or two. Film it in slow motion if you can.

3. Explain: Pairs explain the result using the words horizontal, vertical and independent.

Whiteboard problems

Pairs work through these in order. Ask pairs to hold up their boards after each problem so you can see the whole class at a glance. Use g = 9.8 m/s² and ignore air resistance.

1. Horizontal launch: A ball rolls off a 1.2 m high bench at 2.5 m/s. How long is it in the air, and how far from the bench does it land?

2. Angled launch: A ball is kicked at 20 m/s at 30° above the horizontal from flat ground. Find the time of flight, maximum height and range.

3. Challenge: A stone is thrown at 15 m/s at 40° above the horizontal from the top of a 10 m cliff. How far from the base of the cliff does it land?

Pairs that finish early can work out which launch angle gives the maximum range on flat ground, and explain why.

Target challenge lab

Groups roll a ball down a ramp and off the edge of a bench. Using a phone video in slow motion, they measure the launch speed by timing how long the ball takes to cover a marked distance on the bench just before the edge. They measure the bench height, calculate where the ball should land, and place a cup or target there.

They get one launch. Groups that miss calculate their percentage difference and suggest the most likely reason, such as error in launch speed, release position or the ball rolling instead of sliding. This links straight into uncertainty and validity, which matter for syllabus outcomes and IAs.

After class

The exit ticket tells you who needs help before the next lesson. Homework stays short because the hard practice already happened in class.

Exit ticket (individual, 5 minutes)

1. A ball is thrown horizontally at 12 m/s from a 20 m high building. How far from the base does it land? (g = 9.8 m/s²)

2. In one sentence: why doesn't the horizontal speed change during the flight?

Sort the tickets into three piles: got it, nearly (method right, arithmetic or component error), and not yet (treating the motion as one combined motion). Start the next lesson with a 5-minute small group for the "not yet" pile while the rest start the next topic.

Homework

1. Finish any whiteboard problems not completed in class and check against the worked solutions on the lesson page.

2. Write up the target challenge result: predicted landing spot, actual landing spot, percentage difference, and the main source of error.

3. Optional extension: Rewatch the section of the video on angled launches, then explain why 45° gives the maximum range on flat ground, and why real sports throws are usually lower than 45°.

Teacher notes

Common misconceptions

Students who didn't watch the video

This will happen, so plan for it rather than let it derail the lesson. Set up a "catch-up station" at the back with a device and headphones. They watch the video and complete the guided notes during the first 15 minutes, then join a pair for the whiteboard problems. Don't re-teach the video to the whole class for them. That tells everyone else the homework was optional.

Differentiation

• Support: Give a partly completed components table (horizontal | vertical, with rows for u, a, v, s, t) for students to fill in.

• Extension: Problem 3, the maximum-range question, and comparing their target-challenge error to what air resistance would predict.

• EAL/D students: The guided notes give them a second pass at the vocabulary. Pre-teach component, independent and trajectory.

Answers

Check-for-viewing quiz: 1 (c), 2 (b), 3 (c), 4 (b).

Whiteboard problems:

1. t = 0.49 s, range = 1.24 m

2. u_x = 17.3 m/s, u_y = 10.0 m/s; time of flight = 2.04 s, maximum height = 5.10 m, range = 35.3 m

3. u_x = 11.5 m/s, u_y = 9.64 m/s; solving −10 = 9.64t − 4.9t² gives t = 2.72 s, so it lands 31.2 m from the base

Exit ticket: t = 2.02 s, so it lands 24.2 m from the base.